United States. Congress. Office of Technology Assessment.
Peter E. McKeever
United States. Bureau of Land Management
Bolivia.
Erich Schanze
Indian Bureau of Mines
Unknown Author
Terence Daintith
Colombia.
Centre d'études pour l'action sociale (Kinshasa, Congo)
W.R. Sorley
D. E. Boleneus
United States. General Accounting Office
United States. Office of Surface Mining Reclamation and Enforcement
Trinidad and Tobago.
Philip Daniel
United States. Congress. House. Committee on Interior and Insular Affairs.
Patrick S. Ottinger
United States. Congress. House. Committee on Resources
WWC Engineering